Through a cousin, he started working for the newsreel program Éclair Journal and in 1934 set up his own production company with René Zuber, "Les Films du Compas," later known as, "Roger Leenhardt Films.” As a critic in the journal Esprit, he was considered one of the most perceptive observers of pre-war France and strongly influenced André Bazin and the entire "Nouvelle Vague.” Thanks to his series of articles known as "La petite école du spectateur," cinema became considered as an art and a language in its own right.
Leenhardt also contributed to other journals, such as Fontaine, Les Lettres Françaises, and l'Ecran français, in which in 1948 he delivered his famous cry, "Down with Ford!
In 1949, he fostered the creation of the cinema club Objectif 49 of which he was the co-president with Robert Bresson and Jean Cocteau.
Specialized in short films, the festival brought together the foremost filmmakers, including François Truffaut, Chris Marker, Agnès Varda, Jacques Demy, Roman Polanski, Robert Enrico, and others.
There are two main categories of his work: Portraits of great writers (e.g. François Mauriac, Paul Valéry, Victor Hugo, etc.